The invention relates generally to self-loading firearms, and, more specifically to a housing system for an automatic self-loading rifle or pistol.
For a long time, self-loading rifles have possessed a component which receives a movable breech, which was either forged or machined out of a solid block. The machining for such a component, which formed a primary structural part, required a great expenditure of craftsmanship. On the outside of these breech sections were affixed many functional elements of the weapon. The practice of stamping weapon housings out of sheet metal did not start until the end of the thirties. These sheet metal housings could be fabricated much more quickly and less expensively than before, and yet surrounded most of the functional elements like a shell skeleton. The functional elements were also placed in the interior of the housing, and on this account were protected from damage and contamination. Sheet metal housings have, unfortunately, often been undesirably heavy, particularly with weapons of large dimensions. This weight problem is exacerbated when a particular zone must be reinforced, which usually was carried out by welding on reinforcing members.
Recently, to reduce the weight of the weapons, weapon housings have been made of plastic. In the zones exposed to the principle stresses, however, metal sheathing is once again being used, thereby drastically increasing the weight of the weapon.
For utility weapons, such as are employed for military or police applications, the design effort has been toward weapons of the least possible weight.
One of the main loading factors for the weapon housing is the abutment support of the closure spring of the breech. Fortunately, the spring forces of the breech closure act in the longitudinal direction of the housing, and are therefore well transmitted to the housing walls surrounding the breech spring. More dangerous for the structural strength of the housing, however, is a possible deformation which may be caused by the magazine. The magazine forms a long, lever arm, extending out of the housing from the magazine chamber. This chamber is constructed in the housing and, in the most simple case, is principally an opening, which corresponds to the cross-section of the magazine.
The cross-section of the opening must be large enough to fit the lengths of the provided cartridges. Therefore, the longer the cartridge, the longer the cross-section of the opening must be, which makes the housing more susceptible to twist, since the opening of the magazine chamber breaks the structural advantage of the closed box cross-section of the housing. In order to provide the area of this opening with greater structural strength, the opening is typically encased with a wall structure, which then borders the opening.
This stiffening measure, however, has not always been sufficient. This is particularly the case, when the magazine protrudes out of the housing, and when this protrusion is of a substantial length. In such a case, a more or less transverse loading on the free end of the magazine can lead to the imparting of very high forces to the magazine chamber. This can occur, for instance, if the weapon falls from the bed of a truck to the ground, and then, unfortunately, the magazine separates. An unreinforced, especially thin walled housing can then be bent or even develop fissures.
In the case of a large caliber, self-loading firearm designed for firing shell type munitions with a caliber of some 20 mm, due to the large cartridges which are employed, all parts are inordinately large and heavy. However, a given allowable weight for a user must not be passed. The difficulties arising from this body of problems are increased, when the large caliber rifle carries attached equipment, such as a rapid-fire-system.
The plastic housing of such a large caliber firearm, on this account must be as thin-walled as possible and can only contain the least possible number of metal accessories.
Consideration could be given to increasing the wall thickness in the area of the magazine chamber while refraining from any further metal additions. However, such a measure would be problematic from the standpoint of the casting process. In addition, an area of transition between a larger wall thickness to a lesser wall thickness can form a zone subject to especially great stress, which can lead to a specific location of failure.
In practice, an effort is made to lengthen the walls of the magazine chamber toward the free magazine end, in order, on the one hand, to diminish the lever advantage of the magazine, and on the other hand, to stiffen the housing opening of the magazine entry. In the case of modem rapid-fire weapons, in their conventional construction, (magazine in front of the grip piece) or in the xe2x80x9cbull pupxe2x80x9d fashion, (magazine behind the grip piece) the housing opening for the trigger mechanism is in immediate proximity to the magazine chamber. Additionally, this opening weakens the magazine section, so that the lengthening of the magazine chamber by itself is not enough to correct the above outlined problem in structural strength.
A self-loading rifle is known, from U.S. Pat. No. 4,654,993 where an outer shell construction has been provided so that many parts, such as the trigger mechanism, exhibit a double housing. This rifle, however, possesses no magazine chamber but rather shows complementary rails on the back of the magazine, such as on a retaining yoke made of steel.
Further knowledge gained from the manufacture of traditional repeating or single load rifles with wooden stocks (see, e.g., U.S. Pat. No. 4,385,464), cannot be brought to bear on the issues presented here, since in those cases no housing is present.
The interested reader is referred to the appended claim for concise descriptions of the inventive combinations. Independent claim 1 recites, a housing system for use with a self-loading weapon. The housing system includes a weapon housing having at least one wall at least partially encompassing a magazine chamber; and an inner housing located at least partially within the at least one wall. The inner housing at least partially encompasses at least a portion of the magazine chamber.